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| 1 | jermar | 1 | /* |
| 2 | * Copyright (C) 2001-2004 Jakub Jermar |
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| 3 | * All rights reserved. |
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| 4 | * |
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| 5 | * Redistribution and use in source and binary forms, with or without |
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| 6 | * modification, are permitted provided that the following conditions |
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| 7 | * are met: |
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| 8 | * |
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| 9 | * - Redistributions of source code must retain the above copyright |
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| 10 | * notice, this list of conditions and the following disclaimer. |
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| 11 | * - Redistributions in binary form must reproduce the above copyright |
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| 12 | * notice, this list of conditions and the following disclaimer in the |
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| 13 | * documentation and/or other materials provided with the distribution. |
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| 14 | * - The name of the author may not be used to endorse or promote products |
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| 15 | * derived from this software without specific prior written permission. |
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| 16 | * |
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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| 27 | */ |
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| 28 | |||
| 29 | #include <mm/heap.h> |
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| 30 | #include <synch/spinlock.h> |
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| 31 | #include <func.h> |
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| 32 | #include <memstr.h> |
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| 33 | #include <arch/types.h> |
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| 34 | |||
| 35 | /* |
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| 36 | * First-fit algorithm. |
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| 37 | * Simple, but hopefully correct. |
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| 38 | * Chunks being freed are tested for mergability with their neighbours. |
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| 39 | */ |
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| 40 | |||
| 41 | static chunk_t *chunk0; |
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| 42 | static spinlock_t heaplock; |
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| 43 | |||
| 44 | void heap_init(__address heap, int size) |
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| 45 | { |
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| 46 | spinlock_initialize(&heaplock); |
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| 47 | memsetb(heap,size,0); |
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| 48 | chunk0 = (chunk_t *) heap; |
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| 49 | chunk0->used = 0; |
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| 50 | chunk0->size = size - sizeof(chunk_t); |
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| 51 | chunk0->next = NULL; |
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| 52 | chunk0->prev = NULL; |
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| 53 | } |
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| 54 | |||
| 55 | /* |
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| 56 | * Uses first-fit algorithm. |
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| 57 | */ |
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| 58 | void *malloc(int size) |
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| 59 | { |
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| 60 | pri_t pri; |
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| 61 | chunk_t *x, *y, *z; |
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| 62 | |||
| 63 | if (size == 0) |
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| 64 | panic("malloc: zero-size allocation request"); |
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| 65 | |||
| 66 | x = chunk0; |
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| 67 | pri = cpu_priority_high(); |
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| 68 | spinlock_lock(&heaplock); |
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| 69 | while (x) { |
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| 70 | if (x->used || x->size < size) { |
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| 71 | x = x->next; |
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| 72 | continue; |
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| 73 | } |
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| 74 | |||
| 75 | x->used = 1; |
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| 76 | |||
| 77 | /* |
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| 78 | * If the chunk exactly matches required size or if truncating |
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| 79 | * it would not provide enough space for storing a new chunk |
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| 80 | * header plus at least one byte of data, we are finished. |
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| 81 | */ |
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| 82 | if (x->size < size + sizeof(chunk_t) + 1) { |
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| 83 | spinlock_unlock(&heaplock); |
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| 84 | cpu_priority_restore(pri); |
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| 85 | return &x->data[0]; |
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| 86 | } |
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| 87 | |||
| 88 | /* |
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| 89 | * Truncate x and create a new chunk. |
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| 90 | */ |
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| 91 | y = (chunk_t *) (((__address) x) + size + sizeof(chunk_t)); |
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| 92 | y->used = 0; |
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| 93 | y->size = x->size - size - sizeof(chunk_t); |
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| 94 | y->prev = x; |
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| 95 | y->next = NULL; |
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| 96 | |||
| 97 | if (z = x->next) { |
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| 98 | z->prev = y; |
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| 99 | y->next = z; |
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| 100 | } |
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| 101 | |||
| 102 | x->size = size; |
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| 103 | x->next = y; |
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| 104 | spinlock_unlock(&heaplock); |
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| 105 | cpu_priority_restore(pri); |
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| 106 | |||
| 107 | return &x->data[0]; |
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| 108 | } |
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| 109 | spinlock_unlock(&heaplock); |
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| 110 | cpu_priority_restore(pri); |
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| 111 | return NULL; |
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| 112 | } |
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| 113 | |||
| 114 | void free(void *ptr) |
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| 115 | { |
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| 116 | pri_t pri; |
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| 117 | chunk_t *x, *y, *z; |
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| 118 | |||
| 119 | if (!ptr) |
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| 120 | panic("free on NULL"); |
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| 121 | |||
| 122 | |||
| 123 | y = (chunk_t *) (((__u8 *) ptr) - sizeof(chunk_t)); |
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| 124 | if (y->used != 1) |
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| 125 | panic("freeing unused/damaged chunk"); |
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| 126 | |||
| 127 | pri = cpu_priority_high(); |
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| 128 | spinlock_lock(&heaplock); |
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| 129 | x = y->prev; |
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| 130 | z = y->next; |
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| 131 | /* merge x and y */ |
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| 132 | if (x && !x->used) { |
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| 133 | x->size += y->size + sizeof(chunk_t); |
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| 134 | x->next = z; |
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| 135 | if (z) |
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| 136 | z->prev = x; |
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| 137 | y = x; |
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| 138 | } |
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| 139 | /* merge y and z or merge (x merged with y) and z */ |
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| 140 | if (z && !z->used) { |
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| 141 | y->size += z->size + sizeof(chunk_t); |
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| 142 | y->next = z->next; |
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| 143 | if (z->next) { |
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| 144 | /* y is either y or x */ |
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| 145 | z->next->prev = y; |
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| 146 | } |
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| 147 | } |
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| 148 | y->used = 0; |
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| 149 | spinlock_unlock(&heaplock); |
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| 150 | cpu_priority_restore(pri); |
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| 151 | } |